Inquiring Winemaker

Cold Soak Purists Reveal Reasoning

June 2009

by Tim Patterson

HIGHLIGHTS

Cold soaks (several days of pre-fermentation maceration of crushed or whole grapes before the onset of yeast and ethanol) have become a popular technique in the industry, starting with Pinot Noir and moving beyond.

Practitioners claim benefits in the form of better color extraction, more complex aromatics and flavor compounds, and softer tannin feel.

Beyond anecdotal evidence, the validity of these claims and the science behind them is not yet well understood.

Meanwhile, cold soaks are a very reasonable strategy for certain wine varieties and styles.

If you need further proof that the conceptual apparatus surrounding winemaking isn't quite as tightly constructed as, say, the theories behind rocket science or brain surgery, look no farther than the cold soak.

In the last decade, pre-fermentation cold soaks have gained a prominent place on the leader board of trendy techniques. Starting as a Pinot thing, part of overcoming the notorious--or at least alleged--difficulties in coaxing good wine out of this cranky variety, the practice has been put to use on just about every known red grape at one time or another.

Many excellent outcomes are claimed for the simple act of letting your fruit sit around a few days before you do anything with it: more and better color; more and better aromatics and flavor elements; finer, more mouth-friendly tannins. Talking with several smart winemakers (Pinot folks and otherwise) who swear by the method, I found several somewhat different versions of the story, often accompanied by the acknowledgement that they weren't really all that sure about the underlying chemistry.

You wouldn't want to hear that kind of talk from your brain surgeon as you were going under the knife. But clearly, there's something going on in the cold soak process, probably something useful, and it would be great to know just what the heck it is.

The case for cold soaks

In the bad old days of California Pinot Noir, nobody did cold soaks. They made Pinot Noir the same way they made Cabernet, and the wines showed it. As winemaker Tony Soter, a Pinot pioneer at Etude in the Carneros and who is now working in Oregon, puts it, "This meant that all things being equal, your typical Pinot processed in a typical winery would come out low in color and astringent if not bitter. Way too many of those have been made historically."

Eventually, a handful of wineries tried a different path, implementing what was called Burgundian winemaking, the core of which is gentle handling of the fruit at every step along the way. Cold soaks, part of the protocol, got a major boost, Santa Barbara Pinot specialist Lane Tanner points out, with the greater availability of food-grade dry ice about a decade ago, letting the bin fermentation crowd control temperatures the way the tank producers could with jackets and cold rooms.

The winemakers I talked to, many of them in Pinot-happy Santa Barbara, included several cold soak fans who testified to a number of advantages--some sensory and hedonistic, some more practical and precautionary. We'll start with the sensory part, which is the Grail-worthy piece of the puzzle.

Nearly everyone talked about getting better/more color extraction from the famously color-shy Pinot berries. Karen Steinwachs at Buttonwood Farm in Santa Barbara's Santa Ynez Valley says she gets better color; Wes Hagen at Clos Pepe in the Santa Rita Hills thinks he gets better color; Julie Lumgair at Windsor Oaks Vineyards in the Russian River says her notes over the years document better color, and back in Santa Barbara, veteran Rick Longoria, a winemaker I know to have a healthy skepticism about the latest new thing, has a "gut feeling" that cold soaks help with color.

Up in Napa at Freemark Abbey, Ted Edwards swears by the color extraction advantages for the Bordeaux varieties he works with. And at Fresno State, John Giannini, winemaker for the school's commercial winery, says he certainly got color from cold soaks when he used to work in Sonoma, though he makes less use of the technique working now with valley fruit.

Similarly, cold soakers say they capture more or at least different aromatic and flavor elements, compared to conventional fermentation. Ted Edwards cites bright fruit aromatics; Karen Steinwachs gets blueberries; Wes Hagen finds more aromatics for young wines; Julie Lumgair says that by bottling relatively early, the following August, she's able to capture some of those elusive aromatics and have them persist in the bottle.

Finally, soakers count on courting a better class of tannins. For Rick Longoria, this is the main event. Other folks mentioned it as well, and the thread here seems to be getting more skin tannin and less of the harsher, more bitter/astringent seed tannin.

At least two practical advantages are pretty clear--and often cited. First, time in a cold soak, even a brief one, lets a winemaker get a much better handle on the fruit at hand, enough time to get a tank thoroughly mixed, time for any raisins in the fruit to reveal their sugars, time to get more trustworthy readings on basic wine chemistry than the numbers grabbed in the rush of fruit delivery. And second, extracting some goodies early in the cycle leaves open the option of pressing slightly early and working off the last few Brix in barrel, again minimizing the influence of nasty seed tannin.

All in all, quite a package. To be sure, there are dissenters. "I don't believe cold soak does anything but cause problems," says David Coffaro, a Sonoma County winemaker who has worked with a lot of varieties and a lot of methods over the years. Problems include things like the possibility of spoilage and unwanted spontaneous fermentations kicking off. He's tried the approach on a few occasions, sometimes just with fruit that arrived so cold it had to sit and warm up for a while, and sometimes more intentionally o n the advice of other winemakers, complete with dry ice and everything. His conclusion: "I can't see how it would help anything. I just don't get it."

And even in Santa Barbara, there's Lane Tanner. She began our call by running down the standard list of things cold soaks have been shown to do. But when I asked, "So then I guess this is something you do with your Pinot, right?" her answer was, "No, I'm not really heavy into cold soaks. I think it's a lot of ado about nothing. Pinot has thin skins that break down anyway, and not that much color to get out." In short, why bother? That's why I love talking with Lane Tanner.

Coaxing out the chemistry

Something is going on in those dry-iced bins and cool rooms. At the most basic level, it is manifestly true that some amount of anthocyanin pigment, some aroma and flavor compounds and precursors, and some skin tannin will go into a water-based solution, without the aid of ethanol, and at relatively modest temperatures--like the 50ish range most of my winemakers shoot for. Important stuff does come out under these conditions.

But the harder, more interesting questions are things like: Do you get more stuff or just get it earlier? Wouldn't it come out anyway in the course of a normal fermentation, with the aid of heat and ethanol as a solvent? Are there some things that come out only in a cold soak, and never in a hot ferment? And do the early arrivals always stick around--are they still making the wine better by the end of fermentation, when color always starts to decline, or months later at bottling, or are they a temporary mirage?

For issues like these, we'd like to have more than the personal testimonies of winemakers: We'd like to understand the underlying chemistry, the pre-fermentation kinetics and metabolics. And the short answer is we don't--though some people have offered tantalizing hunches.

More than one of my informants used the phrase, "I'm not a chemist." Wes Hagen had the candor to explain his conversion this way: "To be honest, I do it because it's the way I learned to make Pinot Noir during my first cellar job at Babcock Vineyards--and Bryan Babcock knew so much about enology and chemistry, I took his word for it. So it was a convention that I continued, but now have studied enough to feel comfortable with." Which is exactly how most good winemakers learn their trade. It's also perfectly legitimate to say, as Ted Edwards did, "Just as a cook, I think it works."

Edwards, however, does have a hypothesis about what's going on under the hood. He thinks that some of the forms of enzymatic activity that go on in a water-based soak, breaking down grapes and pulling things out, get short-circuited--his word was "de-natured"--in the presence of rising ethanol.

Similarly, Wes Hagen thinks certain things can best be gotten out of the berry mesocarp before glycolysis (sugar conversion) begins and ethanol shows up. Kathy Joseph at Fiddlehead Cellars, another Santa Barbara soaker, pointed me toward a pair of pieces by Virginia Tech's Bruce Zoecklein, suggesting that the monomeric anthocyanins extracted during cold soaking may (emphasis on may) result in increased finished wine color.

The science here is hardly a slam-dunk, and so I couldn't resist calling Roger Boulton at the University of California, Davis. Boulton is widely known in the industry as the Dr. No of trendy winemaking--as in, "You're perfectly free to believe your technique accomplished what you say, but I hope you can understand that there is no evidence to prove it in the literature."

Sure enough, cold soaks fit nicely into Boulton's category of "belief systems"--constructs based on personal experience, often with a sample size of one, which might or might not be true but are in any case unverified in any rigorous way.

The really interesting question, he says, is why hasn't that rigorous study been done--50 batches of grapes, various cold soak regimens, controls on other aspects of the winemaking, non-stop chemical analysis, evaluation at several points before and after bottling, blind sensory evaluations, the works? Because, he says, the industry just doesn't fund that kind of research.

The Soter synthesis

For my money, the best gloss on the value of cold soaks came in an e-mail exchange with Tony Soter. He started by disclaiming any magic bullet status for cold soaks, but argued they have proven useful, certainly for Pinot Noir. Here's his version:

"We know now (whether empirically or scientifically) that Pinot Noir has relatively low color potential and very high tannin potential. This is compounded by two other miserable aspects of Pinot Noir--its soft berries that easily break up in handling, disgorging their seeds (thus the obsession with Pinot makers about whole fruit), and the fact that for not clear reasons Pinot can ferment very rapidly (almost overnight instead of several days), thus significantly closing the window of opportunity for safe extraction.

"The way to rebalance this double bind is to take advantage of the water soluble nature of pigments, pre-extracting them via cold soak to have them in hand before the wild ride of fermentation. And then de-emphasize the alcohol soluble tannins by managing the fermentation for tannin balance. Handling the fruit in special ways to avoid breaking up the material prematurely is critical to this latter aim. Pressing early can also help, as most makers do."

Makes a lot of sense. And far from being some kind of revolutionary, radical approach, it's a very conservative, risk-averse way to make wine. As Roger Boulton noted in our conversation, this is how Pinot Noir was made in Burgundy for centuries before all the modern overlays: cool weather at harvest time, unheated cellars, spontaneous fermentations that started slowly: nature's own cold soak.

Still , it would be nice to have somebody do the study Boulton sketched in the air, and find out exactly what's going on in those chilly bins. But that would take more than just a grant or two; it would mean doing winemaking in an alternative universe.

Tim Patterson writes about wine and makes his own in Berkeley, Calif. Years of experience as a journalist, combined with a contrarian streak, make him interested in getting to the bottom of wine stories, casting a critical eye on conventional wisdom in the process. Contact him through edit@winesandvines.com.